In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof at least one ink-receiving layer. The ink-receiving layer is typically either a porous layer that imbibes the ink via capillary action, or a polymer layer that swells to absorb the ink. Swellable hydrophilic polymer layers take an undesirably long time to dry. Porous ink-receiving layers are usually composed of inorganic or organic particles bonded together by a binder. The amount of particles in this type of coating is often far above the critical particle volume concentration, which results in high porosity in the coating. During the ink jet printing process, ink droplets are rapidly absorbed into the coating through capillary action and the image is dry-to-touch right after it comes out of the printer. Therefore, porous coatings allow for fast “drying” of the ink, and produce a smear-resistant image.
Ink jet prints, prepared by printing onto ink jet recording elements, are subject to environmental degradation. They are especially vulnerable to damage resulting from contact with water and atmospheric gases such as ozone. The damage resulting from the post imaging contact with water can take the form of water spots resulting from deglossing of the top coat, dye smearing due to unwanted dye diffusion, and even gross dissolution of the image recording layer. Ozone bleaches ink jet dyes resulting in loss of density. To overcome these deficiencies, ink jet prints are often laminated. However, lamination is expensive as it requires a separate roll of material.
U.S. Pat. Nos. 4,785,313 and 4,832,984 relate to an ink jet recording element comprising a support having thereon a fusible, ink-transporting layer and an ink-retaining layer, wherein the ink-retaining layer is non-porous. However, there is a problem with this element in that it has poor image quality.
EP 858,905A1 relates to an ink jet recording element having a porous, outermost layer formed by heat sintering thermoplastic particles such as polyurethane which may contain a slight amount of a hydrophilic binder such as poly(vinyl alcohol). However, there is a problem with this element in that it has poor resistance to mechanical abrasion when it does not contain a hydrophilic binder, and poor water-resistance when it does contain a hydrophilic binder.
U.S. Pat. No. 5,374,475 relates to a record carrier for the receipt of coloring materials comprising a support having thereon an uppermost, porous layer containing particles of a plastic material which may be melted together at their mutual contact areas. While there is a disclosure in this patent of a double layer assembly on the support, the lower layer is not porous since it is described as a layer that absorbs ink via diffusion (Col. 6, lines 3-5). Ink applied to such an element can spread laterally in the porous top layer, resulting in poorer image quality as compared to an element with a porous underlayer as described herein. In addition, there is no disclosure in this patent of the use of a film-forming, hydrophobic binder in this layer, the absence of which results in poor abrasion resistance prior to fusing.
In application Ser. No. 09/955,549 of Wexler, filed Sep. 18, 2001, referred to above, ink jet recording elements are obtained which are useful for the intended purpose. However, there is a problem with such elements after printing and storing under high temperature conditions, in that they tend to block or stick to one another.
It is an object of this invention to provide an ink jet printing method using an ink jet recording element having a fusible protective uppermost layer and ink-retaining underlayer which can be printed with ink jet inks without bleed. It is another object of the invention to provide an ink jet printing method using a porous ink-transporting layer that has good mechanical integrity and is abrasion resistant. It is another object of the invention to provide an ink jet printing method using a protective uppermost ink-transporting layer that is thermally fusible and thereby can be rendered water resistant. It is another object to provide an ink jet printing method using an inkjet recording element that can be thermally fused to provide high density of the printed image. It is another object to provide an ink jet printing method using an ink jet recording element which does not block after storing under high temperature conditions.